Apparatus for the heating of travelling thread or tape-shaped products on a transport roller



g- 1965 A. B. DE LA BRETONIERE 3,200,230

APPARATUS FOR THE HEATING OF TRAVELLING THREAD OR TAPE-SHAPED PR CTS ON A TRANSPORT ROLLER Filed 7, 1963 FIG. 3

INVENTOR. ANDR BENOIT DE LA BRETONIERE TT NEY part of the transport roller.

United States Patent 3,200,230 APPARATUS FGR THE HEATING 0F TRAVEL LING THREAD 0R TAPESHAPED PRGDUCTS ON A TRANSPORT RQLLER Andre B. de la Bretoniere, (losterhcelr, Netherlands, assignor to American Erika Corporation, Enlra, N.C., a corporation of Delaware Filed Jan. 7, 1963, Ser. No. 249,852 Claims priority, application Netherlands, .lan. 12, 1952 8 Claims. (Cl. 219-104?) This invention relates to a material-supporting transport roller, and relates more particularly to a transport roller for supporting thread-like products, said transport roller being provided with internal electromagnetic heating means.

Such a transport roller is especially adapted for use as a draw godet of a drawtwister for warm-drawing threadlike linear polymerization or polycondensation products. By thread-like products is meant yarns, tapes, ribbons, foils, and the like.

Known heated transport rollers of this type are subject to various disadvantages. For example, in one known construction, wherein the roller is heated internally by hot combustion gases, the roller necessarily must have a relatively large diameter. Such a roller cannot readily be operated at high speeds, and the construction of the bearing assembly for the roller and the control of gas to the interior of the roller involve special problems. Such an apparatus has found use only where a large number of .threads or thread wraps are to be placed upon a large,

slowly rotating roller.

It has also been proposedto heat a transport roller by heat-radiating elements surrounding the roller. Such an V apparatus is subject to the disadvantage that the heat-radiating elements form obstructions to the laying of the thread around the roller. Furthermore, there is the possibility that the threads will be locally overheated, which is especially the case if loose fibers or slubs project from the threads.

It has also been proposed in the prior art to heat a transport roller by internally located resistor elements.

. However, in such instances, it is necessary to utilize slip means of internal, radially directed electromagnets having a magnetic field passing at least partly through a metal However, under these conditions, the amount of heat supplied to the roller is dependent primarily upon the rotational speed of the roller, the current supplied to the electromagnets, and, to a lesser extent, on the spacing between the metal part of the roller and the electromagnets. While this arrangement has met with some success, the dependency of the quantity of heat upon the rotational speed of the roller is objectionable. Furthermore, in accordance with this previous proposal, a rotary magnetic field could be achieved only by physical rotation of the electromagnets. Also, to provide means for roating the electromagnes an undesirably complex construction is required.

It is a principal object of the present invention to provide an improved heated transport roller'for thread-like Still another object of this invention is to provide improved electromagnetic heating means for a transport roller which enable the roller to be heated While stationary.

A further object of this invention is to provide improved electromagnetic heating means for a transport roller wherein stationary electromagnets effectively form a rotary magnetic field.

A still further object of this invention is to provide a transport roller with improved heating means including electromagnets supplied with balanced polyphase current of regulatable frequency.

These and other objects and advantages of this invention will become more apparent from the following description.

in one embodiment of this invention, a transport roller having a material-supporting outer cylindrical casing is driven by an axial drive shaft. A plurality of stationary electromagnets are essentially symmetrically positioned within the outer casing of the roller so that at least a portion of the magnetic flux from the electromagnets passes within a portion of the outer casing of the roller. A balanced polyphase current is supplied to the electromagnets, and regulator means are provided to vary the frequency of the current supplied to the electromagnets.

in normal operation, energy is generated by relative movement between the magnetic field and a conductive part of the transport roller. Such movement is accompanied by the dissipation of energy in the form of heat which causes the temperature of the transport roller to rise. The ultimate temperature of the roller is determined by an equilibrium between the amount of heat generated in the roller and the quantity of heat given off by the roller to the surroundings. The dissipation of energy in the roller originates from various sources. For example, if the conductive part of the roller consists of a ferromagnetic material, then repeated pole changing, or magnetization and demagnetization, of the ferromagnetic material caused by relative rotation of the roller with respect to the magnetic field will result in release of heat in the form of hysteresis losses. Hysteresis losses are generally contributed to molecular friction induced within the material On the other hand, it the conductive part of the transport roller is copper or a material having similar properties, then the heat produced is substantially due to eddy currents or voltages induced in the material by the magnetic field. Normally, the heat evolved results from a combination of hysteresis and eddy current losses.

In the event that the frequency of the polyphase current is considerably higher than the rotational speed of the roller, then the amount of heat supplied per unit of time is not affected by fluctuations in the rotational speed of conjunction with the accompanying drawings, wherein FIGURE 1 is a longitudinal sectional view through a transport roller in accordance with one embodiment of the present invention;

FIGURE 2 is a cross-sectional view taken substantially along the line II-II of FIGURE 1; and

FIGURE 3 is a somewhat diagrammatic view showing apparatus for supplying current to the electromagnets within the roller of FIGURE 1.

Referring now to the drawings, wherein like numerals designate like parts in the several views, and more particularly to FIGURE 1, reference numeral 1 designates a transport roller or draw godet of a drawtwister. The

roller 1 is driven by an axially located shaft 2 of a synchronous electric motor 3 of which only a part thereof is illustrated in FIGURE 1. e As clearly shown, the free end of shaft 2 is provided with a tapered portion 4 which is received within a conical hub 6 of roller 1. The tapered portion 4 terminates in a threaded portion which receives a nut for securing shaft 2 and roller 1 in driving engagement. The roller 1 is provided with an outwardly opening central recess to receive nut 5. A thin layer of 'a suitable heat-insulating material 7 is provided between the complementary conicalsurfaces of the tapered portion 4 and the conical hub 6 to minimize heat transfer from roller 1 to shaft 2.

Roller 1 has a substantially cylindrical material-suppotringouter casing which is provided at one end with "a flange 8. The flange 8 serves to prevent the threadlike products from slipping off the roller and becoming fouled in the vicinity of the motor 3. It Will be appreciated that similar restraining means could be provided at the other end of roller 1 if desired.

A generally cylindrical support member 10 is mounted coaxially around shaft 2 and hub 6. The support member '10 is rigidly secured to the electric motor 3 by a circumferential flange 9 and socket head screws 11 or other suitable securing means. In accordance with this invention, cylindrical support member 10 is provided with an en- 'larged body portion 12 having three longitudinally extending grooves. An electromagnet 13 is cemented or otherwise rigidly positioned within each groove. As clearly shown in FIGURE 2, the poles of electromagnets 13 ex- Qtendv essentially'radially with respect to shaft 2 and are symmetrically arranged at an angle of 120 relative to each other. Each electromagnet includes a magnetizing coil 15. V

A metallic sleeve 14 is clamped or otherwise integrally secured to the inside surface of the cylindrical outer serve to adjust the stator field of the polyphase current generator. Also, while the coils of the electromagnets have been described as wired in a delta connection, it is apparent that'the coils could also be wired in a Y connection.

Frequency regulation may also be effected by other A known methodsrfor example, by pole changing Where the casing of roller 1. In a specific embodiment of this inven-. tion, sleeve 14 is made of electrically pure copper having a thickness of 2 mm, and is separated from the adjacent magnetic poles by a clearance of 0.2 mm. It is apparent that the particular material used for sleeve 14 may be varied in accordance with design requirements. As indicated previously, the properties of the material used determine whether the roller will be heated primarily by hysteresis or eddy current losses, or by a combination thereof.

Referring to FIGURE 3, coils 15 are wired in a balanced delta connection. The apices of the delta are connected through a suitable electrical circuit including three rheostats to the terminals of a three-phasecurrent generator 17. The rheostats 16 are mechanically intercoupled so that the voltages at the apices of the delta connection are maintained equal by coordinated adjustments of the settings of rheostats 16.

Generator 17 is driven by a shaft 19 which is connected to a suitable motor (not shown). A hand wheel 18 con- .trols a built-in speed regulator operatively interconnected between shaft 19 and generator 17. The built-in speed aregulator may include reduction gearing or any other suitable speed regulating mechanism. By adjustment of planation, it is to be understood that the scope of this invention is limited only to the extent defined in the appended claims.

What is-claimed is:

1. Improved heating apparatus for a driven transport roller having a material-supporting casing, comprising a plurality of electromagnets positioned within and spaced from said casing, said electromagnets being positioned so that at least a portion of the magnetic flux from the electromagnets passes Within aflconductive part of said casing for heating said roller, means connecting said electromagnets electrically, means for, supplying polyphase current successively to said electromagnets to produce a rotating magnetic flux, and regulator means to vary the frequency :of said current to control the amount of heat supplied to said roller independently of the rotary speed thereof.

2. Apparatus as defined in claim 1 wherein said means for supplying current include a polyphase generator.

3. Apparatus as defined in claim 2, wherein said regulator means include speed control means operatively connected with said generator.

'4. Apparatus as defined in claim 3 wherein said regulator means further include coupled rheostats operatively connected between said electromagnets and said generator.

5. In a driven transport roller having a materialsupporting casing and having internal heating means, the improvement consisting of a plurality of essentially symmetrically arranged electromagnets positioned within and spaced from said casing, said electromagnets being positioned so that at least a portion of the magnetic flux from the electromagnets passes within a conductivepart of said casing for heating said roller, means connecting said electromagnets electrically, means for supplying a polyphase current successively to said electromagnets to produce a rotating magnetic flux, and regulator means to vary the frequency of. said current independently of the rotary speed of said roller.

6. Improved heating apparatus for a driven roller having a'material-supporting outer casing, comprising three essentially symmetrically arranged electromagnets positioned within and spaced from said outer'casing, said j electromagnets having the poles thereof essentially radially directedand being positioned so that at least a portion hand wheel 18, which controls the built-in speed regulav.tor, the frequency of the polyphase current supplied by generator 17 may be varied within predetermined limits.

The regulation of the heat supplied to the roller is believed apparent from the foregoing description. For example, it Will be appreciated that the quantity of heat to be generated in roller 1 may be initially coarsely adjusted by the .hand wheel 18, and a fine adjustment of the quantity of heat may be provided by subsequently adjusting "the settings of rheostats 16.

It is apparent that the presentinvention' is susceptible "to many changes and modifications. For example, a variable transformer maybe provided in lieuof the rheostats. This variable transformer may,if desired, also of the magnetic flux from the electromagnets passes Within a conductive part of saidbuter casing for heating said roller, means connecting said electromagnets electrically,

means for supplying three-phase current successively to said electromagnets to produce a rotating magnetic flux,

1 and regulator means to vary the frequency of said current independently of the rotary speed of said roller.

'7. Apparatus as defined in claim 6, wherein said electromagnets are'connected in a balanced delta.

8. A transport roller assembly comprising a roller having an axial hub and a cylindrical material-supporting casing, a drive shaft operatively engaging said hub, a stationary support member disposed concentrically about said hub and said drive shaft, a plurality of essentially radially disposed electromagnets secured to said support member and spaced inwardly from said casing, said electromagnets being positioned so that at least a portion of the mag- 3,200,230 5 6 netic flux from the electromagnets passes Within a con- References Cited by the Examiner ductive part of said casing for heating said roller, means UNITED STATES PATENTS connecting said electromagnets electrically, means including generator means for supplyi g a P yp Current 2: 52 n successively to said electromagnet t Pr a rotating 5 2968711 1/61 Zu n 219- 10 61 magnetic fluX, and regulator mean to vary the frequency 014 11 12/ 1 gfA th 219. 1() 49 of said current to regulate the heat supplied to said roller u independently of the rotary speed thereof. RICHARD M. WOOD, Primary Examiner. 

1. IMPROVED HEATING APPARATUS FOR A DRIVEN TRANSPORT ROLLER HAVING A MATERIAL-SUPPORTING CASING, COMPRISING A PLURALITY OF ELECTROMAGNETS POSITIONED WITHIN AND SPACED FROM SAID CASING, SAID ELECTROMAGNETS BEING POSITIONED SO THAT AT LEAST A PORTION OF THE MAGNETICA FLUX FROM THE ELECTROMAGNETS PASSES WITHIN A CONDUCTIVE PART OF SAID CASING FOR HEATING SAID ROLLER, MEANS CONNECING SAID ELECTROMAGNETS ELECTRICALLY, MEANS FOR SUPPLYING POLYPHASE CURRENT SUCCESSIVELY TO SAID ELECTROMAGNETS TO PRODUCE A ROTATING MAGNETIC FLUX, AND REGULATOR MEANS TO VARY THE FREQUENCY OF SAID CURRENT TO CONTROL THE AMOUNT OF HEAT SUPPLIED TO SAID ROLLER INDEPENDENTLY OF THE ROTARY SPEED THEREOF. 